A brief summary of changes made to Python 2.5.4 source to get it working on
Symbian:

-  Changed the definition of the PyAPI_DATA and all the python header files
   which used the earlier PyAPI_DATA to use its new form as DLL data export is
   not supported on Symbian. A workaround is to have functions that return
   pointers to the data and macros that hide the calls made to these functions.
   This is enabled when the macro EXPORT_DATA_AS_FUNCTIONS is defined.

- To handle recursions causing stack overflows gracefully stack checks are done
  more frequently.

- Disabled creation of byte compiled files when python modules are loaded

- On the Symbian platform a value greater than 1e49 limits the precision to 28
  above which it crashes the interpreter with panic User24. Added a check so
  that OverflowError is raised for values greater than 1e49 with precision
  greater than 28.

- Modified python's core memory APIs so that it defines macros which can
  be used to set custom malloc/realloc/free functions.

- Python regression suite tests for modules that were not supported on Symbian,
  were disabled by adding a platform check in the test itself. Limits were
  reduced in tests which assumed a huge stack was available and were failing
  with stack overflow error.

- Implementation of the Python TLS API on top of the POSIX threads TLS API.
  Also added PyThread_AtExit which provides extension modules to register their
  functions which cleanup resources at thread exit.

- A new exception SymbianError is added which is used to set Symbian errors.

- dynload_shlib is modified to load the function at ordinal 1 which corresponds
  to the init function (Symbian uses ordinal numbers to identify functions).

- The default file system encoding is set to 'utf-8'

- socketmodule is patched to workaround the OpenC bug related to getaddrinfo.

- A separate copy of site.py and pyconfig.h is maintained in Symbian directory
  as the changes done to these files is applicable only to Symbian platform

- The classification of core python modules into builtin and PYDs is specified
  in the modules.cfg file in Symbian\src. This file is parsed by
  module_config_parser.py which generates and modifies the individual extension
  and python dll build files. Minor changes were done to some modules' init
  function and headers to facilitate building them as PYDs.

- To support co-existence of 1.4.x and 1.9.x Python runtimes, the binaries of
  the latter version are prefixed with 'kf_' and the import hook in site.py is
  modified to look for the renamed binary.

- Python core files modsupport.c and getargs.c are patched to support va_list's
  structure definition which is defined in gcce.h

- Added access_points() and set_default_access_point() to the socket module
  for accessing the list of available access points and to set the default
  access point.

- linesep changed to '\n' from '\r\n' in os.py.

- Maintaining linked lists to track all memory allocations and open DLLs. These
  are later used during application exit to cleanup all the resources.